Silicon manufacturing apparatus

Abstract

A polycrystalline silicon production apparatus is provided whereby when deposited silicon is caused to drip down into an underlying collection part by heating the reaction tube inner surface at a temperature equal to or above the melting point of silicon, the silicon melt can be prevented from solidifying at a lower end portion of the reaction tube due to temperature lowering at the lower end portion. When a reaction tube is heated with a high frequency heating coil, the temperature lowering at a lower end portion of the reaction tube is prevented through temperature lowering prevention means which may be an infrared device capable of heating the outer periphery of the lower end portion by means of infrared rays, or which may be a lower end coil that is constituted by a coil near the lower end of the high frequency heating coil and has an increased heating intensity relative to an upper coil.

1. A polycrystalline silicon production apparatus comprising:
 a reaction tube comprising a carbon material; 
 a gas supply opening through which a chlorosilane and hydrogen are supplied from above the reaction tube; and 
 a high frequency heating coil provided around the outer periphery of the reaction tube, wherein the high frequency heating coil heats at least part of the reaction tube including a lower end portion to a temperature equal to or in excess of the melting point of silicon; 
 wherein the silicon production apparatus further includes temperature lowering prevention means for preventing temperature lowering at the lower end portion of the reaction tube during heating with the high frequency heating coil, 
 the temperature lowering prevention means being disposed at a lower position from the lower end portion of the reaction tube and being provided with a heating means, the temperature lowering prevention means heats atmosphere near the lower end portion of the reaction tube. 
 
     
     
       2. The silicon production apparatus according to  claim 1 , wherein the temperature lowering prevention means is an infrared device capable of heating the outer periphery of the reaction tube lower end portion by means of infrared rays. 
     
     
       3. The silicon production apparatus according to  claim 2 , wherein the infrared device comprises:
 an infrared member comprising a carbon material, the infrared member being provided around the outer periphery of the reaction tube lower end portion away from the lower end portion; and 
 the high frequency heating coil provided around the outer periphery of the infrared member so as to heat the infrared member. 
 
     
     
       4. The silicon production apparatus according to  claim 1 , wherein a thermal insulating member is provided around the outer periphery of the reaction tube to prevent heat release from the reaction tube. 
     
     
       5. The silicon production apparatus according to  claim 1 , wherein the lower end portion of the reaction tube ranges up to intersections between:
 straight lines extending from the intersection of a horizontal surface leveling with the lowermost end of the reaction tube and the central axis of the reaction tube, the straight lines each having an angle of 45 degrees relative to the horizontal surface; and 
 perpendicular lines extending along the inner peripheral surface of the reaction tube in the axial direction, the perpendicular lines originating from the shortest straight line of the straight lines halving an opening shape of the reaction tube.